In typical hub-and-spoke networks it is desirable for the spokes not to be used as transit paths between two hubs. In many networks, this statement is true at all times. A link state protocol maintains a full topology of the nodes in the domain, which means that it will find paths through the spokes if available and use them. Current best practices result in the spokes being used as transit only as a last resort by either adjusting the metrics or providing a link between the hubs.
The existing methods for routing in hub-spoke network topologies avoid using spoke routers in the transit path between hub routers. In general, the occurrence of the spoke routers in the transit path between hub routers is prevented by using a link (physical/logical) between the hubs. This mechanism works until the link goes down.